The present invention relates to a tool attaching/detaching device, and more particularly to an attaching/detaching device for attaching/detaching a circular tool such as a grindstone for a grinder without using any other auxiliary tool.
In general, a working machine such as a grinder which performs working by rotating a tool is well known. In such a device, a rotary tool is mounted thereon by an attaching/detaching mechanism.
FIG. 7 is a cross sectional view showing a recently proposed attaching/detaching device, and FIG. 8 is a sectional view taken along the line VIII--VIII of FIG. 7 (Japanese Publication of International Application No. Hei 2-502359). Three radially extending pins 102, 102, 102 are embedded in a ring member 101 so as to extend radially inwardly. Three support members 103 are interposed within the ring member while keeping a space therebetween. Stoppers 105 are provided at suitable positions within the space 104. A coil spring 106 is interposed between each stopper 105 and the associated radial pin 102. Each ball 107 is rotatably disposed opposite to the radial pin 102 and the stopper 105. A recess 101a which is engageable with the ball 107 is formed in an inner surface of the ring member 101. A clamp nut 108 is threadedly engageable with a spindle 109 is inserted into the inner portion of the support members 103. As shown in FIG. 8, a slide member 110 is slidingly provided around a body portion 108a of the clamp nut 108. The slide member 110 is in contact with a rotary tool 111 and is adapted to clamp the rotary tool 111 in cooperation with an inner flanged portion of a gear shaft 112.
The operation for mounting the attaching/detaching device onto the spindle 109 will be explained.
First of all, the body portion 108a of the clamp nut 108 is engaged with the spindle 109 to thereby threadedly advance the clamp nut 108 and the ring member 101 is rotated to locate the balls 107 in the position shown in FIG. 7. Then, as shown in FIG. 8, the slide member 110 is stopped at a position in contact with the rotary tool 111 to thereby perform temporary fastening. Subsequently, a motor (not shown) is operated so that the spindle 109 is rotated. In this case, since the spindle 109 is rotated in a direction in which the clamp nut 108 is fastened, the fastening is assured to complete the mounting operation of the rotary tool 111. When the device is loosened, the balls 107 are located in the recesses.
In such an arrangement, since the balls are only located in two positions, that is, the position where the balls are in contact with the pins 102 and the position where the balls are located in the recesses 101a, it is impossible to manually fasten the device completely and it is necessary to use the fastening torque of the motor to rotate the spindle 109. On the other hand, such an arrangement needs the increased number of the mechanical parts for depressing the slide member and the clamp nut through the support members. This leads to difficulty in machining the mechanical parts.